I have a 1995 Buick Lesabre that started running.

I have a 1995 Buick lesabre that started running rough. It has shut down on us, lights all lit up and then restarted. We changed the fuel pump, the cam positions sensor, new plugs, filter and when it starts up it will idle fine but when you push on the gas in cuts out and sounds almost like a backfire in the engine. As long as it idles it does fine. What else can we check to fix this car. It only has 84, 000 miles on it. I would like to keep it around awhile. (But running!)